Retirement savings calculator — how much you will have and how much you need

How to use the retirement savings calculator

1. Enter your Current age, your Retirement age and the age you want to Plan for money to last until.
2. Enter your Retirement savings today and your Monthly saving. Add a yearly Increase if you plan to raise it with your pay.
3. Set the Return before retirement, the Return during retirement and Inflation.
4. Enter the Yearly income you want in retirement and your expected Social Security and pensions per year, both in today’s dollars.
5. Read your projected savings, the amount you need, the shortfall or surplus, the monthly saving that would close the gap, and the age your money lasts to.

What it does and when to use it

This calculator answers two questions at once. How much am I on course to have when I retire? And how much do I actually need for the life I want? It then turns the difference into a monthly figure you can act on and shows how long your money would last.

It suits a yearly check-up, or deciding whether to raise your 401(k) or IRA contributions. It also helps you see what retiring a few years earlier or later is worth. It works with your total retirement savings across accounts. For a single workplace plan with an employer match, the 401(k) calculator goes into more detail.

How it works

Saving phase. Your monthly saving is added at the end of each month. It rises once a year by your increase percentage. The balance grows at the monthly equivalent of your pre-retirement return, (1 + return)^(1/12) − 1.

Income you need. The yearly gap is the income you want minus Social Security and pensions, in today’s dollars. It is inflated to your retirement age: first-year withdrawal = gap × (1 + inflation)^years to retirement. In retirement it keeps rising with inflation every year.

Savings needed. This is the lump sum at retirement that pays every withdrawal from retirement to your planning age. Each withdrawal is taken at the start of the year, and what is left earns your retirement return:

Needed = Σ (t = 0 … N − 1) of W × (1 + inflation)^t ÷ (1 + retirement return)^t

where W is the first-year withdrawal and N the number of retirement years.

Monthly saving needed. This is the level monthly amount that, added to your current savings, grows to exactly the amount needed:

m = (Needed − savings × (1 + i)^M) × i ÷ ((1 + i)^M − 1)

where i is the monthly return and M the number of months to retirement.

Money lasts until. Starting from your projected savings, the calculator takes each year’s withdrawal and grows the rest. It reports the age at which a full withdrawal is no longer possible.

Worked examples

The default plan. Age 35, $50,000 saved, $500 a month, retiring at 67 and planning to 90. It assumes a 6% return before retirement, 4% after and 2.5% inflation. The goal is $50,000 a year with $20,000 from Social Security, both in today’s dollars. Savings grow to $882,847.05 by 67, about $400,610 in today’s money. The $30,000 gap becomes a first withdrawal of $66,112.71, and the savings needed at 67 are $1,302,036.97. The shortfall is $419,190. Saving $874.16 a month from now would close it, and on the current plan the money lasts until about age 81.

Retiring at 70 instead. With everything else the same, savings reach $1,071,106 and the amount needed falls to $1,244,713. The monthly saving needed drops to $626.39, and the money lasts until about 86.

A check you can do by hand. Age 40, nothing saved, $1,000 a month, retiring at 65 and planning to 85, with returns and inflation set to 0%. You save $1,000 × 300 months = $300,000. You need $24,000 a year for 20 years, so the savings needed are $480,000.00. The gap is $180,000, which is $1,600 a month over 300 months. The $300,000 covers 12.5 years, so it runs out at about 77.

Saving $900 a month. The default plan with $900 instead of $500 reaches $1,330,989, a surplus of $28,952.24 over the amount needed, and lasts to about 90.

Limits and tips

• Returns and inflation are assumptions. The calculator uses steady rates. Real markets move unevenly, and a fall just before or after you retire matters more than the average.
• Taxes are not deducted. Withdrawals from traditional 401(k)s and IRAs are taxed as income, so the income you want should include the tax you expect to pay. Roth withdrawals that meet the rules are tax-free.
• Social Security is your estimate. The calculator does not work out benefits. Use your statement from the Social Security Administration.
• Fees are not included. Lower your return assumptions by your yearly fund and advice fees.
• Health care and long-term care can be large and uneven. Consider adding a margin to the income you want.
• Contribution limits apply in real accounts. In 2026 you can defer up to $24,500 into a 401(k), or $32,500 at 50 or older ($35,750 at 60 to 63), and put up to $7,500 into an IRA ($8,600 at 50 or older). A monthly saving above what your accounts allow would have to go into a taxable account.

Related tools

The 401(k) calculator projects a workplace plan with your employer’s match and the IRS limits year by year. The US paycheck calculator shows how a bigger pre-tax contribution changes your take-home pay. The compound interest calculator shows the growth of any lump sum or regular deposit, and the inflation calculator converts future dollars into today’s money.